Sage 50 Accounts Integration

I have been having this problem for a few weeks now and can't appear to find any solution to it. It HAS been working in the past OK so I know something must have changed but I can't find what.

Trying to Create a link from a Company in Act 2011 to Sage 50 2011. We get to the wizard that asks if you want to create the company as a Customer/Supplier. Clicking onto Next pauses for 20 seconds then says a Sage Act error 'Unable to connect to accounting application'

Sage 50 Accounts is installed locally and can access the data on the server fine. Act is installed locally with data on the server fine.

If I sit at the server itself the link works perfect.

I have reset SData numerous times and it is setup on the client PC exactly the same as the server.